Big Alpine Fault rupture due in the next century or two

The Alpine Fault is a big feature of South Island geography and seismic activity. It last ruptured in 1717 and there is a big earthquake, on average, about every 300 years, but the times vary so there is thought to be about a 30% risk of the next ‘Big One’ in the next fifty years.

When I was woken up by an earthquake in the middle of the night on 4 September 2010 I wondered if it was ‘the big one’ – it was big enough but that was centred close to Christchurch.

This image clearly shows the fault running up the West Coast, where the Australian plate dives under and drives up the Southern Alps which line along the rising edge of the Pacific Plate.

Video simulations demonstrate widespread destruction across the South Island if New Zealand’s most dangerous fault line ruptures, and there’s evidence the country is due for another big one.

Project Alpine Fault Magnitude 8 (AF8) released a series of videos on Wednesday, warning there’s compelling geological evidence to show it produces a significant earthquake of magnitude eight or greater every 300 years on average.

The last rupture was believed to have happened in 1717.

That sounds dramatically imminent, but the intervals have actually varied between 140 and 510 years, so it may or may not happen in our lifetimes.

The Alpine Fault is the biggest but just one of many fault lines affecting New Zealand. This is a few years old but is a good look at plate tectonics in New Zealand:

Dunedin is about as far as you can get in the South Island from the fault but when the big one strikes it is certain to be felt here (we feel larger Fiordland earthquakes as well as the bigger Christchurch quakes) and it is likely to have major effects across the South Island, and also in the lower North Island.

11 Comments

David

I wish they would shut up with their predictions, they are unsettling given what we lived through but at the end of the day they are nothing more than a mathematical equation. What if the big one however many years ago settled the thing for eons and took most of the pressure out ?
Earthquakes dont follow a particular time scale and saying something may happen in the next few hundred years is like saying I dont know what the hell I am talking about, they should join the treasury and just leave us alone.

Alan Wilkinson

Alan Wilkinson

David

I guess sooner or later they will get something right, I am hoping its the report I saw last week about going into a cooling period because of the rapid decline in sun activity then I can sit in my armchair in 40 years time look back and chuckle.

Griff

David

Gee mention climate change and Griff appears out of nowhere armed with pretty charts albeit meaningless ones but I appreciate the effort.
You are wasting your time Griff the whole thing is a massive hoax, I have dumped my solar and stocks and investing in thermals and stockpiling vitamin D tablets and looking forward to ice skating across the Thames like my ancestors.

Griff

Yess Dave science is a hoax.
In your deluded little world .
I could give you the papers behind the chart and a few more links .
But.
I know actually finding out about reality gives you RWNJ’s cognitive dissonance so I did not bother.

Your comment on climate change goes well with your first comment on this thread.
Lets just pretend scary things cant happen so Dave will not get frightened to much ….EH

David

Climate changes..meh.. who cares its been happening since time started and here we are richer and healthier than ever.
I am more a ban plastic bags, low emission cars, keep the rivers clean, recycle everything possible, hydro power sort of a guy.

sorethumb

Possibly one feature of our risk is that the Pacific plate is schist to greywache (further from the fault). When the Eastern face fell away from Mt Cook the underlying rock was described a “weetbix”. Granite mountains would stay more intact. The big landslide under the viaduct at Arthurs Pass came down 2000 years ago. Bugger being a train driver on the Midland line.

Alan Wilkinson

Gezza

Pretty well everywhere in NZ will feel it if there’s a large rupture I’ve read – & you can bet Welly will get whacked hard. Would be surprised if it set several faults off here – the Cook & Welly are riddled with them. I went straight on to Geonet when we felt the first big rock n roll from the first Sedden event series a couple of years back. Here, it was like sitting on an overloaded washing machine on the spin cycle.

Same thing happened with the Kaikoura quakes, but I kept refreshing the page every minute – never seen anything like it before. Quakes were rippling up & down the Lower NI & Upper SI, back & forth – epicentred all over the show. It collapsed some of the far stream bank which had been sodden with rain & recently butchered by council workers.